Experiments are underway using nerve tissue cultures to a variety of experimental agents, to freeze-fracturing, to autoradiographic analysis, and to electron microscopic examination in order to study: a. Aspects of ion economy in myelinated and unmyelinated nerve fibers in an attempt to determine the conditions under which these fibers degenerate and to examine the accompanying morphological changes. b. Aspects of neuronal Golgi function, particularly in an attempt to determine if there is a Na-K pump in the Golgi membrane and/or in other intracellular membranes in neurons. c. Aspects of synaptogenesis in tissue culture, especially to determine (1) Whether synapses can form between parts of the nervous system not normally interconnected and (2) Whether synapse formation can be blocked by the use of agents active at the neuron surface. d. The cytology of the growth cone, particularly its membrane properties and its mechanisms of uptake of protein markers. e. If it may be feasible to prepare fetal nervous tissues for tissue culture and then to transplant these preparations into animals in an attempt to foster regeneration in the mature central nervous system.